GFR-estimation by serum creatinine during glucocorticosteroid therapy.

BACKGROUND

While glucocorticosteroids (GCS) are widely used in patients with kidney disease, little is known about their effect on serum creatinine, the most commonly used endogenous marker of kidney function.

METHODS

We assessed the effect of GCS on the relationship between estimated GFR using the Schwartz equation (eGFR) and measured GFR using a single-injection inulin clearance (Cin) in children both in a paired analysis and a cross-sectional study. Primary outcome variable was the difference between eGFR and Cin (ΔGFR) in a paired analysis involving 22 patients during and off GCS treatment (mean GFR 103.8 ml/min/1.73 m, mean prednisone dose 34.8 mg/m/day). In a cross-sectional analysis in 42 patients receiving GCS (mean dose of 25.7 mg/m/day), a dose-dependent effect was explored using univariate and multivariate linear regression of various variables including GCS dosage with serum creatinine as dependent variable.

RESULTS

The paired analysis showed no significant difference in ΔGFR with or without GCS [- 23 (SD 53) vs. - 9 (SD 41) ml/min/1.73 m, p = 0.203]. Stepwise multivariate linear regression analysis showed a significant correlation between age and Cin, while GCS dose was not related to serum creatinine.

CONCLUSION

GCS use had no significant effect on serum creatinine as a marker for kidney function in a mixed population of renal outpatient clinic children.